Sound box



Apr. 24, 1923.

E. FLETCHER SOUND BOX Filed Sent. 8, 1919 Patented Apr. 24, I823.

entree sraras I itans earner ELMER FLETCHER, or cnrcnso, rLLInors, Assrsnon o rnnronna-wrcxns 00., or CHICAGO, ILLINOIS, A COELPORATION or rLLInors.

sounn BOX.

Application filed September 8, 1919. Serial No. 822,554.

To all whom it may concern: I

Be it known that I, ELMER Fm'rorinn, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Sound Boxes, of which the following is a full, clear, and exact description.

The invention relates to sound boxes for phonographs or recorders One object of the invention s to prov de an improved sound box in which provision is made for deflecting the sound between the diaphragm and the tone-arm, so that the 15.sound will be diffused and amplified and also mellowed to eliminate sharp metallic noises or sounds.

Another object of the invention is to provide an improved construction by which the wall of the sound-box will be rendered more rigid than it is in boxes of usual construction.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings: Fig. 1 is a side elevation of a phonograph embodying the invention. Fig. 2 is a section taken on l ne 2--2 of Fig. 1. Fig. 3 is a detail section through the sound-box taken on line 3-3 of Fig. 2.

The invention is shown as applied to a reproducing instrument comprising a sound box 7 which is provided with a chamber 8 in which a diaphragm 9 is held in any suitable manner, as exemplified by the elastic rings 10 and 11. A needle 15 is suitably mounted on a support 16 which issecured to the diaphragm in any suitable manner.

as well understood in the art. A wall 18, integral with the sound box, is disposed therein and in back of the diaphragm 9. This wall has openings 19 the'rethrough near the margin and is spaced from the diaphragm. A back 5 is separately formed from the box, is secured thereto by screws 22 and is provided with a boss 12 which is adapted for connection to a tone-arm 14:. The inner face 6 of the back plate 5 is spaced from the wall 18 leaving a chamber 6 between the wall and the back which is in communication with the tone-arm through openings 21 adjacent the central -portion of the back, the latter being extended across the open end of the tone-arm. As a result of this construction, the vibrations of the diaphragm, the amplitude of which'is greatest at its center, do notpass directly from the centerof the diaphragm to the outlet, but are deflected to pass outwardly, thence 'backwardly through the perforations 19 and thence inwardly to and through openings 21 intothe tone arm. In practice, it has been found that this construction causes the sound to be amplified and mellowed so that the metallic tones are eliminated.

In practice, it has been found that by rigidifying the walls of the chambers, through which thesound passes, the tones tain this result a central lug 25 is formed on the back of the wall 18 and is extended to abut against and engage the back between the outlet openings 21. In practice, the back is formed so that normally the lug and said wall will engage slightly before the screws 22 are in position to clamp the margin of the back against the box, so that,

when the screws are tightened, the metal in the wall 18 and the back 5 will be put under slight tension. This causes the back 5 and the wall 18 to be mutually supporting, so that they will act as rigid walls for the sound passages.

In practice, it has also been found thatit [improves the instrument to render the wall of the sound-box rigid, and for this purpose, the inner periphery of the box is circular and the exterior is polygonal or polyhedral, as shown at 26. This results in an excess of metal without undue enlargement which renders-the sound box comparatively rigid.

The invention is not to be understood will be purified and improved, and to obsound into the chamber between the plate and the wall, and means for centrally supporting said wall.

2. In a sound box, the combination of a case having a back provided with a centrally disposed sound-outlet connection, a diaphragm in the boin an intermediate wall marginally connected to the case spaced "from the back and from the diaphragm having openings near the periphery to conduct the sound into the chamber between the plate and the wall, and means between the back and said Wall for supporting the wall.

3. In a sound-box the combination of a case having a back provided with a centrally disposed sound-outlet connection, a diaphragm in the box an intermediate wall marginallyconnected to the case spaced from the back and from the diaphragm having openings near the periphery to conduct the sound into the chamber between the plate and the wall, and a connection between the wall and the back for mutually supporting them.

4. In a sound-box the combination of a case having; a back provided with a centrally disposed sound-outlet connection, a diaphragm in the box, an intermediate wall in the case spaced from the back and from the diaphragm having openings near the periphery to conduct the sound into the chamber between the plate and the wall, a lugbetween the wall and the back, and means for putting the back and wall under tension.

ELMER FLETCHER. 

